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Abstract:

An optical deflector which deflects incident light, includes an optical
deflection element which deflects the incident light when a distribution
of internal refraction indexes of the optical deflection element is
modulated. The light incident on the optical deflection element is
emitted from the optical deflection element after passing through the
optical deflection element a plurality of times.

Claims:

1. An optical deflector which deflects incident light, the optical
deflector comprising an optical deflection element which deflects the
incident light when a distribution of internal refraction indexes of the
optical deflection element is modulated, wherein the light incident on
the optical deflection element is emitted from the optical deflection
element after passing through the optical deflection element a plurality
of times.

2. A liquid crystal display apparatus comprising: the optical deflector
according to claim 1; and a liquid crystal panel which is provided at one
side of the optical deflector, and on which the light emitted from the
optical deflector is incident, wherein the light emitted from the liquid
crystal panel is alternately collected onto a right eye and a left eye of
a viewer viewing the liquid crystal panel.

3. The liquid crystal display apparatus according to claim 2, further
comprising: a reflective plate which is provided at an other side of the
optical deflector, and which specularly reflects light; and a light
emitting unit which is provided between the liquid crystal panel and the
optical deflector, and which emits light, wherein the light emitted from
the light emitting unit passes through the optical deflector, is
specularly reflected by the reflective plate, passes through the optical
deflector again, and is incident on the liquid crystal panel.

4. The liquid crystal display apparatus according to claim 3, further
comprising an optical element which is provided between the light
emitting unit and the reflective plate, and which changes a traveling
direction of light.

5. The liquid crystal display apparatus according to claim 4, wherein the
optical element is a prism sheet or a Fresnel sheet.

6. An optical deflection apparatus comprising: the optical deflector
according to claim 1; a polarizing reflective sheet which is provided at
one side of the optical deflector, which reflects light having a first
polarization direction, and which transmits light having a second
polarization direction orthogonal to the first polarization direction; a
reflective plate which is provided at an other side of the optical
deflector, and which specularly reflects light; a λ/4 plate
provided between the optical deflector and the reflective plate; and a
light emitting unit which is provided between the polarizing reflective
sheet and the λ/4 plate, and which emits, toward the polarizing
reflective sheet, the light having the first polarization direction.

7. A liquid crystal display apparatus comprising: the optical deflection
apparatus according to claim 6; and a liquid crystal panel on which light
emitted from the optical deflection apparatus is incident, wherein the
light emitted from the light emitting unit of the optical deflection
apparatus passes through the optical deflector of the optical deflection
apparatus a plurality of times, is emitted from the polarizing reflective
sheet of the optical deflection apparatus, and is incident on the liquid
crystal panel, and the light emitted from the liquid crystal panel is
alternately collected onto a right eye and a left eye of a viewer viewing
the liquid crystal panel.

8. The liquid crystal display apparatus according to claim 7, wherein the
light emitting unit is capable of switching a polarization direction of
the light emitted from the light emitting unit between the first
polarization direction and the second polarization direction orthogonal
to the first polarization direction.

9. The liquid crystal display apparatus according to claim 7, wherein a
polarization direction of the light emitted from the light emitting unit
includes a polarization component of the first polarization direction and
a polarization component of the second polarization direction orthogonal
to the first polarization direction.

10. The liquid crystal display apparatus according to claim 8, wherein
the optical deflector includes: a first optical deflector provided
between the light emitting unit and the polarizing reflective sheet; and
a second optical deflector provided between the light emitting unit and
the λ/4 plate of the optical deflection apparatus.

11. The liquid crystal display apparatus according to claim 7, further
comprising an optical element which is provided between the reflective
plate of the optical deflection apparatus and the light emitting unit,
and which changes a traveling direction of light.

12. The liquid crystal display apparatus according to claim 11, wherein
the optical element is a prism sheet or a Fresnel sheet.

13. The liquid crystal display apparatus according to claim 11, wherein
the optical element is an active optical element which is capable of
modulating a collection point of the light emitted from the liquid
crystal panel, according to movement of the right eye and the left eye of
the viewer.

14. The liquid crystal display apparatus according to claim 7, further
comprising a diffuser panel provided between the optical deflection
apparatus and the liquid crystal panel, wherein the diffuser panel is
switchable between a diffusion state where light is diffused and a
non-diffusion state where light is transmitted without diffusion.

15. An optical deflection apparatus comprising: the optical deflector
according to claim 1; a reflective plate which is provided at one side of
the optical deflector, and which specularly reflects light; a λ/4
plate provided between the optical deflector and the reflective plate; a
polarizing reflective sheet which is provided at an other side of the
optical deflector, and which reflects light having a first polarization
direction and transmits light having a second polarization direction
orthogonal to the first polarization direction; and a light emitting unit
which is provided between the optical deflector and the polarizing
reflective sheet, and which emits, toward the optical deflector, the
light having the second polarization direction.

16. A liquid crystal display apparatus comprising: the optical deflection
apparatus according to claim 15; and a liquid crystal panel on which
light emitted from the optical deflection apparatus is incident, wherein
the light emitted from the light emitting unit of the optical deflection
apparatus passes through the optical deflector of the optical deflection
apparatus a plurality of times, is emitted from the polarizing reflective
sheet of the optical deflection apparatus, and is incident on the liquid
crystal panel, and the light emitted from the liquid crystal panel is
alternately collected onto a right eye and a left eye of a viewer viewing
the liquid crystal panel.

17. The liquid crystal display apparatus according to claim 16, wherein
the light emitting unit is capable of switching a polarization direction
of the light emitted from the light emitting unit between the first
polarization direction and the second polarization direction orthogonal
to the first polarization direction.

18. The liquid crystal display apparatus according to claim 16, wherein a
polarization direction of the light emitted from the light emitting unit
includes a polarization component of the first polarization direction and
a polarization component of the second polarization direction orthogonal
to the first polarization direction.

19. The liquid crystal display apparatus according to claim 16, further
comprising a diffuser panel provided between the optical deflection
apparatus and the liquid crystal panel, wherein the diffuser panel is
switchable between a diffusion state where light is diffused and a
non-diffusion state where light is transmitted without diffusion.

20. The liquid crystal display apparatus according to claim 16, further
comprising an optical element which is provided between the reflective
plate of the optical deflection apparatus and the light emitting unit,
and which changes a traveling direction of light.

21. The liquid crystal display apparatus according to claim 20, wherein
the optical element is a prism sheet or a Fresnel sheet.

22. The liquid crystal display apparatus according to claim 9, wherein
the optical deflector includes: a first optical deflector provided
between the light emitting unit and the polarizing reflective sheet; and
a second optical deflector provided between the light emitting unit and
the λ/4 plate of the optical deflection apparatus.

Description:

TECHNICAL FIELD

[0001] The present disclosure relates to optical deflectors and optical
deflection apparatuses which deflect incident light, and liquid crystal
display apparatuses using the optical deflectors and the optical
deflection apparatuses.

BACKGROUND ART

[0002] Various optical deflectors which deflect incident light have
conventionally been studied. Optical deflectors are devices indispensable
to, for example, laser scanners used in laser printers or the like.
Examples of conventional optical deflectors include polygon scanners,
galvanometer scanners, and MEMS mirrors. However, since such polygon
scanners, galvanometer scanners, MEMS mirrors, or the like include a
mobile unit (mechanical mechanism) for moving parts, there is a problem
in that a failure easily occurs. For this reason, there is demand for the
development of optical deflectors capable of deflecting light without
including a mobile unit.

[0003] In response to that demand, an optical deflector as disclosed in
Patent Literature (PTL) 1 below has been proposed. This optical deflector
does not include a mobile unit, and deflects light with use of the fact
that the refractive indexes of liquid crystals are modulated by
application of voltage. Through this, it is possible to reduce the
occurrence of failures and achieve high reliability.

[0004] Now, a conventional optical deflector will be described with
reference to FIGS. 14A and 14B. FIG. 14A is a cross-sectional view of a
conventional optical deflector, and FIG. 14B is a cross-sectional view of
the optical deflector taken along line A-A in FIG. 14A. An optical
deflector 50 shown in FIGS. 14A and 14B includes an optical deflection
element 501 and three pairs of electrodes 502a, 502b, and 502c provided
in the periphery of the optical deflection element 501. The optical
deflection element 501 includes a liquid crystal 503 having a triangular
shape in cross section and a dielectric 504 having a shape complementary
to that of the liquid crystal 503. The dielectric 504 is provided on the
inclined face side of the liquid crystal 503, as a result of which the
optical deflection element 501 as a whole is configured in a rectangular
shape in cross section. The dielectric 504 may be made of, for example, a
polymeric resin such as a plastic, or glass. The three pairs of
electrodes 502a, 502b, and 502c are each provided such that the two
electrodes face each other with the optical deflection element 501
therebetween.

[0005] Light is incident on the optical deflection element 501 as
indicated by an arrow 505 in FIG. 14A. The refractive index of the liquid
crystal 503 is modulated by application of voltage (including zero
voltage) between each of the three pairs of electrodes 502a, 502b, and
502c, and the light incident on the optical deflection element 501 is
deflected. When a refractive index NL of the liquid crystal 503 is higher
than a refractive index ND of the dielectric 504, light is refracted in a
direction indicated by an arrow 505h in FIG. 14A. When the refractive
index NL of the liquid crystal 503 is lower than the refractive index ND
of the dielectric 504, light is refracted in a direction indicated by an
arrow 505m in FIG. 14A. In this way, the light deflected inside the
optical deflection element 501 is emitted from the optical deflection
element 501. When the refractive index NL of the liquid crystal 503 and
the refractive index ND of the dielectric 504 are the same value, light
travels in a straight direction indicated by an arrow 505s in FIG. 14A
without being refracted.

[0006] The response speed of the optical deflection element 501 when
deflecting light depends on the height of the liquid crystal 503.
According to PTL 1, the liquid crystal 503 having a height of 20 μm or
less achieves a response speed of 100 μsec or less, and the liquid
crystal 503 having a height of 15 μm or less achieves a response speed
of 30 μsec or less. Here, by changing the difference between the
refractive index NL of the liquid crystal 503 and the refractive index ND
of the dielectric 504 by approximately 0.2, light can be deflected at an
angle of approximately 30 degrees.

[0007] Furthermore, PTL 2 below discloses a liquid crystal display
apparatus which provides three dimensional (3D) images using the above
optical deflector. FIG. 14C is a cross-sectional view of a conventional
liquid crystal display apparatus. A liquid crystal display apparatus 60
in FIG. 14C includes an optical deflector 601, a light guide plate 602, a
light source 603, a liquid crystal panel 604, a pair of stereo cameras
605a and 605b, and a control unit 606. The optical deflector 601 includes
a plurality of the optical deflection elements 501 arranged horizontally.
The control unit 606 controls the liquid crystal panel 604, the optical
deflector 601, the light source 603, and the pair of stereo cameras 605a,
and 605b. Light emitted from the light source 603 is incident on the
lateral face of the light guide plate 602, propagates through the light
guide plate 602, is directed upward in a substantially vertical direction
by the prism shaped bottom of the light guide plate 602, and then is
emitted from the top face of the light guide plate 602. The light,
incident on the optical deflector 601 substantially vertically, is
deflected at a different deflection angle for each optical deflection
element 501 at predetermined timing, thereby being collected onto a right
eye 607a of a viewer 607. In synchronization with the predetermined
timing, the control unit 606 causes the liquid crystal panel 604 to
display a right-eye image. After the above predetermined timing, light is
deflected by the optical deflector 601 to be collected onto a left eye
607b of the viewer 607. In synchronization with this timing, the control
unit 606 causes the liquid crystal panel 604 to display a left-eye image.
By alternately switching between the images displayed on the liquid
crystal panel 604 at a predetermined cycle (for example, 8.3 msec: 120
Hz), the viewer 607 perceives the images displayed on the liquid crystal
panel 604 as 3D images.

[0008] In a case where the position of the viewer 607 shifts, the control
unit 606 adjusts the angle of light deflected the deflector 601, based on
the positions of the eyes 607a and 607b of the viewer 607 detected by the
pair of stereo cameras 605a and 605b. As a result, it is possible to
continuously provide right-eye images to the right eye 607a and left-eye
images to the left eye 607b.

[0012] However, in the conventional liquid crystal display apparatus 60,
the amount of the refractive index of the optical deflector 601 that can
be modulated is small, and the light deflection angle is up to
approximately 30 degrees. Hence, the viewer 607 needs to be positioned
far from the liquid crystal panel 604. Furthermore, in a case where the
position of the viewer 607 significantly shifts, light from the liquid
crystal panel 604 cannot follow the movement of the viewer 607. As
described above, the conventional liquid crystal display apparatus 60
provides a limited range (visual field) in which 3D images are viewable.

[0013] The present disclosure has been conceived to solve the conventional
problem. The present disclosure has an object to provide an optical
deflector and an optical deflection apparatus which allow greater light
deflection angle. Another object is to provide a liquid crystal display
apparatus which displays high-quality 3D images, with greater visual
field where 3D images and the like are viewable and with reduced
crosstalk.

Solution to Problem

[0014] In order to achieve the above objects, an optical deflector
according to one aspect of the present disclosure deflects incident light
and includes an optical deflection element which deflects the incident
light when a distribution of internal refraction indexes of the optical
deflection element is modulated, and the light incident on the optical
deflection element is emitted from the optical deflection element after
passing through the optical deflection element a plurality of times.

Advantageous Effects of Invention

[0015] The optical deflector and the optical deflection apparatus
disclosed herein allows greater light deflection angle. Furthermore, the
liquid crystal display apparatus disclosed herein provides a greater
visual field in which 3D images and the like are viewable, and displays,
on a liquid crystal panel, high-quality 3D images and the like with
reduced crosstalk.

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1A is a cross-sectional view of an optical deflector according
to Embodiment 1.

[0017] FIG. 1B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 1.

[0018]FIG. 2 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 2.

[0019]FIG. 3 is a cross-sectional view of an optical deflection apparatus
according to Embodiment 3.

[0020]FIG. 4A is a cross-sectional view of an optical deflection
apparatus according to Embodiment 4.

[0021]FIG. 4B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 4.

[0022] FIG. 5 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 5.

[0023]FIG. 6A is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 6.

[0024] FIG. 6B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 6.

[0025] FIG. 7 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 7.

[0026] FIG. 8 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 8.

[0027]FIG. 9 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 9.

[0028] FIG. 10A is a cross-sectional view of an optical deflection
apparatus according to Embodiment 10.

[0029] FIG. 10B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 10.

[0030]FIG. 11 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 11.

[0031] FIG. 12 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 12.

[0032] FIG. 13 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 13.

[0033]FIG. 14A is a cross-sectional view of a conventional optical
deflector.

[0034]FIG. 14B is a cross-sectional view of the optical deflector taken
along line A-A in FIG. 14A.

[0036] FIG. 15A is a cross-sectional view of a liquid crystal display
apparatus including a lens array, according to a comparison example.

[0037] FIG. 15B is an enlarged cross-sectional view of the lens array
shown in FIG. 15A.

DESCRIPTION OF EMBODIMENTS

Background to Embodiments of the Present Disclosure

[0038] Prior to describing Embodiments, a description is given of the
problems, found by the Inventors, of a conventional liquid crystal
display apparatus. It is to be noted that the following description helps
understanding the present disclosure, however, various conditions and the
like described below do not limit the present disclosure.

[0039] FIG. 15A is a cross-sectional view of a liquid crystal display
apparatus including a lens array, according to a comparison example. A
liquid crystal display apparatus 70 shown in FIG. 15A includes a
double-layered lens array 608 between an optical deflector 601 and a
liquid crystal panel 604. For example, the light deflection angle can be
increased by using the double-layered lens array 608 as disclosed in PTL
3.

[0040] However, the liquid crystal display apparatus 70 shown in FIG. 15A
has a following problem. FIG. 15B is an enlarged cross-sectional view of
the lens array shown in FIG. 15A. As shown in FIG. 15B, the lens array
608 includes beam reducers each of which includes two lenses 608a and
608b. The diameter of beam (light), which is obtained after the light
deflection angle is increased, generally decreases by a magnification
factor of the deflection angle. For example, in the case of an optical
system where the lens array 608 increases incident angle θ1 of beam
to angle θ2 by θ2/θ1, beam diameter W2, which is
obtained after the deflection angle is increased, decreases to
1/(θ2/θ1) of beam diameter W1 which is obtained before the
light deflection angle is increased. Hence, excessive magnification
factor of the deflection angle results in uneven illuminated area of the
liquid crystal panel 604, as shown in FIG. 15B, including unilluminated
liquid crystal pixels. Furthermore, in a case where the beam diameter W2
is too small, beam spreads due to diffraction, causing crosstalk which
reduces image quality.

[0041] In order to solve such problems, an optical deflector according to
one aspect of the present disclosure deflects incident light and includes
an optical deflection element which deflects the incident light when a
distribution of internal refraction indexes of the optical deflection
element is modulated, and the light incident on the optical deflection
element is emitted from the optical deflection element after passing
through the optical deflection element a plurality of times.

[0042] According to the aspect, the deflection angle of light which passes
through the same deflection element a plurality of times is, for example,
approximately a few times greater than the deflection angle of light
which passes through an optical deflection element only once. As a
result, it is possible to increase the light deflection angle with a
relatively-simple structure.

[0043] The liquid crystal display apparatus according to one aspect of the
present disclosure includes: the optical deflector according to Claim 1;
and a liquid crystal panel which is provided at one side of the optical
deflector, and on which the light emitted from the optical deflector is
incident, and the light emitted from the liquid crystal panel is
alternately collected onto a right eye and a left eye of a viewer viewing
the liquid crystal panel.

[0044] According to the aspect, the deflection angle of light emitted from
the optical deflector can be increased, allowing a greater visual field
in which 3D images and the like are viewable. Furthermore, it is possible
to display high-quality 3D images and the like on a liquid crystal panel,
with reduced crosstalk.

[0045] For example, it may be that the liquid crystal display apparatus
according to one aspect of the present disclosure, further includes: a
reflective plate which is provided at an other side of the optical
deflector, and which specularly reflects light; and a light emitting unit
which is provided between the liquid crystal panel and the optical
deflector, and which emits light, and the light emitted from the light
emitting unit passes through the optical deflector, is specularly
reflected by the reflective plate, passes through the optical deflector
again, and is incident on the liquid crystal panel.

[0046] According to the aspect, light is emitted from the optical
deflector after passing through the same optical deflector a plurality of
times, and thus, the deflection angle can be increased.

[0047] For example, it may be that the liquid crystal display apparatus
according to one aspect of the present disclosure further includes an
optical element which is provided between the light emitting unit and the
reflective plate, and which changes a traveling direction of light.

[0048] According to the aspect, by deflecting light using an optical
element, the light can be deflected toward the right eye and the left eye
of the viewer, with a small internal refractive index distribution of the
optical deflection element. As a result, for example, it is possible to
achieve a liquid crystal display apparatus which consumes lower power.

[0049] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, the optical element may be a prism
sheet or a Fresnel sheet.

[0050] According to the aspect, it is possible that the optical element is
formed of a prism sheet or a Fresnel sheet.

[0051] An optical deflection apparatus according to one aspect of the
present disclosure includes: the optical deflector according to Claim 1;
a polarizing reflective sheet which is provided at one side of the
optical deflector, which reflects light having a first polarization
direction, and which transmits light having a second polarization
direction orthogonal to the first polarization direction; a reflective
plate which is provided at an other side of the optical deflector, and
which specularly reflects light; a λ/4 plate provided between the
optical deflector and the reflective plate; and a light emitting unit
which is provided between the polarizing reflective sheet and the
λ/4 plate, and which emits, toward the polarizing reflective sheet,
the light having the first polarization direction.

[0052] According to the aspect, the deflection angle of light which passes
through the same optical deflector a plurality of times is, for example,
approximately a few times greater than the deflection angle of light
which passes through the optical deflector only once. As a result, it is
possible to increase the light deflection angle with a relatively-simple
structure.

[0053] A liquid crystal display apparatus according to one aspect of the
present disclosure includes the optical deflection apparatus according to
Claim 6; and a liquid crystal panel on which light emitted from the
optical deflection apparatus is incident, and the light emitted from the
light emitting unit of the optical deflection apparatus passes through
the optical deflector of the optical deflection apparatus a plurality of
times, is emitted from the polarizing reflective sheet of the optical
deflection apparatus, and is incident on the liquid crystal panel, and
the light emitted from the liquid crystal panel is alternately collected
onto a right eye and a left eye of a viewer viewing the liquid crystal
panel.

[0054] According to the aspect, the deflection angle of light emitted from
the optical deflector can be increased, allowing a greater visual field
in which 3D images and the like are viewable. Furthermore, it is possible
to display high-quality 3D images and the like on a liquid crystal panel,
with reduced crosstalk.

[0055] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, it may be that the light emitting
unit is capable of switching a polarization direction of the light
emitted from the light emitting unit between the first polarization
direction and the second polarization direction orthogonal to the first
polarization direction.

[0056] According to the aspect, a viewer which is capable of viewing 3D
images and the like displayed on the display panel can be switched
appropriately between a plurality of viewers.

[0057] For example, in the liquid crystal display apparatus according to
one aspect of the present invention, it may be that a polarization
direction of the light emitted from the light emitting unit includes a
polarization component of the first polarization direction and a
polarization component of the second polarization direction orthogonal to
the first polarization direction.

[0058] According to the aspect, a plurality of viewers can concurrently
view 3D images and the like displayed on the liquid crystal panel.

[0059] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, it may be that the optical
deflector includes: a first optical deflector provided between the light
emitting unit and the polarizing reflective sheet; and a second optical
deflector provided between the light emitting unit and the λ/4
plate of the optical deflection apparatus.

[0060] According to the aspect, even in a case where a plurality of
viewers are located at different positions, light can be deflected
independently toward each of the viewers.

[0061] For example, the liquid crystal display apparatus according to one
aspect of the present disclosure, may further include an optical element
which is provided between the reflective plate of the optical deflection
apparatus and the light emitting unit, and which changes a traveling
direction of light.

[0062] According to the aspect, by deflecting light using an optical
element, the light can be deflected toward the right eye and the left eye
of the viewer with a small internal refractive index distribution of the
optical deflection element. As a result, for example, it is possible to
achieve a liquid crystal display apparatus which consumes lower power.

[0063] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, the optical element may be a prism
sheet or a Fresnel sheet.

[0064] According to the aspect, it is possible that the optical element is
formed of a prism sheet or a Fresnel sheet.

[0065] For example, in the liquid crystal display apparatus according to
one aspect of the present invention, it may be that the optical element
is an active optical element which is capable of modulating a collection
point of the light emitted from the liquid crystal panel, according to
movement of the right eye and the left eye of the viewer.

[0066] According to the aspect, it is possible that the optical deflector
deflects light toward the right eye and the left eye of the viewer and
the active optical element follows the light collection point moved along
with the movement of the right eye and the left eye of the viewer. As a
result, it is possible to achieve a liquid crystal display apparatus
which provides a greater visual field, and which allows the light
collection point to be easily followed even in a case where the position
of the viewer shifts.

[0067] For example, it may be that the liquid crystal display apparatus
according to one aspect of the present invention, further includes a
diffuser panel provided between the optical deflection apparatus and the
liquid crystal panel, and the diffuser panel is switchable between a
diffusion state where light is diffused and a non-diffusion state where
light is transmitted without diffusion.

[0068] According to the aspect, it is possible to achieve a liquid crystal
display apparatus which is switchable between 2D display and 3D display
or privacy display.

[0069] An optical deflection apparatus according to one aspect of the
present disclosure, includes the optical deflector according to Claim 1;
a reflective plate which is provided at one side of the optical
deflector, and which specularly reflects light; a λ/4 plate
provided between the optical deflector and the reflective plate; a
polarizing reflective sheet which is provided at an other side of the
optical deflector, and which reflects light having a first polarization
direction and transmits light having a second polarization direction
orthogonal to the first polarization direction; and a light emitting unit
which is provided between the optical deflector and the polarizing
reflective sheet, and which emits, toward the optical deflector, the
light having the second polarization direction.

[0070] According to the aspect, the deflection angle of light which passes
through the same optical deflector a plurality of times is, for example,
approximately a few times greater than the deflection angle of light
which passes through the optical deflector only once. As a result, it is
possible to increase the light deflection angle with a relatively-simple
structure.

[0071] A liquid crystal display apparatus according to one aspect of the
present disclosure includes the optical deflection apparatus according to
Claim 15; and a liquid crystal panel on which light emitted from the
optical deflection apparatus is incident. The light emitted from the
light emitting unit of the optical deflection apparatus passes through
the optical deflector of the optical deflection apparatus a plurality of
times, is emitted from the polarizing reflective sheet of the optical
deflection apparatus, and is incident on the liquid crystal panel, and
the light emitted from the liquid crystal panel is alternately collected
onto a right eye and a left eye of a viewer viewing the liquid crystal
panel.

[0072] According to the aspect, the deflection angle of light emitted from
the optical deflection apparatus can be increased, allowing a greater
visual field in which 3D images and the like are viewable. Furthermore,
it is possible to display high-quality 3D images and the like on a liquid
crystal panel, with reduced crosstalk.

[0073] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, it may be that the light emitting
unit is capable of switching a polarization direction of the light
emitted from the light emitting unit between the first polarization
direction and the second polarization direction orthogonal to the first
polarization direction.

[0074] According to the aspect, a viewer who is capable of viewing 3D
images and the like displayed on the liquid crystal panel can be switched
appropriately between a plurality of viewers.

[0075] For example, in the liquid crystal display apparatus according to
one aspect of the present invention, it may be that a polarization
direction of the light emitted from the light emitting unit includes a
polarization component of the first polarization direction and a
polarization component of the second polarization direction orthogonal to
the first polarization direction.

[0076] According to the aspect, a plurality of viewers can concurrently
view 3D images and the like displayed on the liquid crystal panel.

[0077] For example, it may be that the liquid crystal display apparatus
according to one aspect of the present invention, further includes a
diffuser panel provided between the optical deflection apparatus and the
liquid crystal panel, and the diffuser panel is switchable between a
diffusion state where light is diffused and a non-diffusion state where
light is transmitted without diffusion.

[0078] According to the aspect, it is possible to achieve a liquid crystal
display apparatus which is switchable between 2D display and 3D display
or privacy display.

[0079] For example, the liquid crystal display apparatus according to one
aspect of the present disclosure, may further include an optical element
which is provided between the reflective plate of the optical deflection
apparatus and the light emitting unit, and which changes a traveling
direction of light.

[0080] According to the aspect, by deflecting light using an optical
element, the light can be deflected toward the right eye and the left eye
of the viewer with a small internal refractive index distribution of the
optical deflection element. As a result, for example, it is possible to
achieve a liquid crystal display apparatus which consumes lower power.

[0081] For example, in the liquid crystal display apparatus according to
one aspect of the present disclosure, the optical element may be a prism
sheet or a Fresnel sheet.

[0082] With this, it is possible that the optical element is formed of a
prism sheet or a Fresnel sheet.

EMBODIMENTS

[0083] Hereinafter, detailed descriptions are given of embodiments of the
present disclosure, referring to the accompanying Drawings. Each of the
embodiments described below shows a general or specific example. The
numerical values, shapes, materials, structural elements, the arrangement
of the structural elements, steps, the processing order of the steps etc.
shown in the following embodiments are mere examples, and therefore do
not limit the scope of the appended Claims and their equivalents. The
present disclosure is defined by the appended claims. Therefore, among
the structural elements in the following embodiments, structural elements
not recited in any one of the independent claims are described as
arbitrary structural elements.

Embodiment 1

Structure of Optical Deflector

[0084] FIG. 1A is a cross-sectional view of an optical deflector according
to Embodiment 1. As shown in FIG. 1A, an optical deflector 10 according
to Embodiment 1 includes an optical deflection element 101. At one side
of the optical deflection element 101, a reflective plate 102 is
provided. The following describes the structure of the optical deflection
element 101 and the reflective plate 102.

[0085] The optical deflection element 101 includes a liquid crystal 103
having a triangular shape in cross section and a dielectric 104 having a
shape complementary to that of the liquid crystal 103. The dielectric 104
is provided on the inclined face side of the liquid crystal 103. As a
result, the optical deflection element 101 has a rectangular shape in
cross section as a whole. The dielectric 104 may be made of, for example,
a polymeric resin such as a plastic, or glass.

[0086] Furthermore, a pair of electrodes (not shown) is provided for
applying voltage to the liquid crystal 103 of the optical deflection
element 101. The pair of electrodes is provided such that the two
electrodes face each other with the optical deflection element 101
therebetween. By controlling the voltage applied between the pair of
electrodes, a refractive index NL of the liquid crystal 103 can be
modulated at a predetermined modulation range. For example, when a first
voltage is applied between the pair of electrodes, the refractive index
NL of the liquid crystal 103 is higher than the refractive index ND of
the dielectric 104. When a second voltage different from the first
voltage is applied between the pair of electrodes, the refractive index
NL of the liquid crystal 103 is lower than the refractive index ND of the
dielectric 104. When a third voltage, which is different from the first
voltage and the second voltage, is applied between the pair of
electrodes, the refractive index NL of the liquid crystal 103 is the same
value as the refractive index ND of the dielectric 104. In such a manner,
the internal refractive index distribution of the optical deflection
element 101 is modulated. It is to be noted that each of the first
voltage, the second voltage, and the third voltage has a certain level of
voltage, but may be a zero voltage.

[0087] The reflective plate 102 is provided facing the dielectric 104 with
a space therebetween. The surface of the reflective plate 102 which faces
the dielectric 104 has, for example, a mirrored reflective plane 102a.
The reflective plane 102a has a function to specularly reflect light. As
described later, light incident on the optical deflector 101 passes
through the optical deflector 101, is emitted from the optical deflector
101, is reflected by the reflective plate 102, and then is incident on
the optical deflector 101 again. The reflective plate 102 may be included
in the optical deflector 10 together with the optical deflection element
101.

[0088] Next, a description is given of a method for deflecting light
performed by the optical deflector 10 according to Embodiment 1. A light
source (not shown) is provided on the light incident side of the optical
deflector 10. As indicated by an arrow 105 in FIG. 1A, light emitted from
the light source is incident on the incidence end face (lower face in
FIG. 1A) of the liquid crystal 103 in a substantially vertical direction.

[0089] For example, when the third voltage is applied between the pair of
electrodes, the refractive index NL of the liquid crystal 103 is the same
value as that of the refractive index ND of the dielectric 104. As a
result, the light incident on the incidence end face of the liquid
crystal 103 travels straight as indicated by an arrow 105s in FIG. 1A
without being refracted at the interface between the liquid crystal 103
and the dielectric 104. For example, when the first voltage is applied
between the pair of electrodes, the refractive index NL of the liquid
crystal 103 is higher than the refractive index ND of the dielectric 104.
As a result, the light is refracted at the interface between the liquid
crystal 103 and the dielectric 104, as indicated by an arrow 105h in FIG.
1A. Furthermore, for example, when the second voltage is applied between
the pair of electrodes, the refractive index NL of the liquid crystal 103
is lower than the refractive index ND of the dielectric 104. As a result,
the light is refracted at the interface between the liquid crystal 103
and the dielectric 104, as indicated by an arrow 105m in FIG. 1A.

[0090] Here, a description is given of a case where the refractive index
NL of the liquid crystal 103 is higher than the refractive index ND of
the dielectric 104. For example, in a case where the liquid crystal 103
has a refractive index NL of 1.5, a height H of 15 μm, and a width W1
of 50 μm, and the dielectric 104 has a refractive index ND of 1.4,
light 11 incident on the incidence end face of the liquid crystal 103
substantially vertically is refracted at the interface between the liquid
crystal 103 and the dielectric 104 at an angle of θ1=1.2 degrees.
Then, the light travels through the dielectric 104, and is emitted into
the air at an angle of θ2=1.7 degrees. The light which is emitted
into the air is specularly reflected by the reflective plane 102a of the
reflective plate 102, is incident on the dielectric 104 again at an angle
of θ2=1.7 degrees and then travels through the dielectric 104.
After that, the light is refracted at the interface between the
dielectric 104 and the liquid crystal 103 at an angle of θ3=2.3
degrees, and is emitted into the air at an angle of θ4=3.4 degrees,
that is, the angle twice as large as the angle 82.

[0091] Hence, the light deflection angle of the optical deflector 10
according to Embodiment 1 is the angle θ4=3.4 degrees. The light
deflection angle refers to an angle at which light finally emitted from
the optical deflector 10 is deflected relative to the vertical direction
(up-down direction in FIG. 1A). Furthermore, each of the angles θ1
to θ4 is an angle relative to the vertical direction.

[0092] As described, with the optical deflector 10 according to Embodiment
1, light incident on the optical deflection element 101 passes through
the optical deflection element 101 twice and then is emitted from the
optical deflection element 101. The deflection angle θ4 of light
which passes through the optical deflection element 101 twice is twice as
large as the deflection angle θ2 of light which passes through the
optical deflection element 101 only once. Hence, the optical deflector 10
according to Embodiment 1 is capable of doubling the light deflection
angle with a relatively simple structure.

[0093] In a case where the refractive index NL of the liquid crystal 103
is lower than the refractive index ND of the dielectric 104, too, the
light deflection angle θ4 can be increased in the similar manner to
above. Furthermore, in a case where the reflective plate 102 is provided
facing the liquid crystal 103, too, the light deflection angle θ4
can be increased in the similar manner to above.

[0094] The optical deflector 10 according to Embodiment 1 has such a
structure where light passes through the optical deflection element 101
twice; however, it is easily understood that allowing light to pass
through the optical deflection element 101 three times or more further
increases the light deflection angle.

[0095] The optical deflector 10 according to Embodiment 1 uses the
reflective plate 102 to allow light to pass through the optical
deflection element 101 twice; however, any elements other than the
reflective plate 102 may be used.

[0096] In this description, the term "pass through" refers to that light
incident on the optical deflection element 101 travels through the
optical deflection element 101, and then is emitted from the optical
deflection element 101.

(Structure of Liquid Crystal Display Apparatus)

[0097] FIG. 1B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 1. As shown in FIG. 1B, a liquid
crystal display apparatus 20 according to Embodiment 1 includes an
optical deflector 10A, a liquid crystal panel 106, a light emitting unit
107, a reflective plate 102, a pair of stereo cameras 108a and 108b, and
a control unit 109. The liquid crystal display apparatus 20 according to
Embodiment 1 is, for example, a tablet 3D display which allows viewers to
view 3D images with their naked eyes without wearing dedicated glasses.

[0098] The optical deflector 10A includes an array of the optical
deflection elements 101. Each of the optical deflection elements 101 has
a structure similar to that of the optical deflection element 101 in FIG.
1A. As a result, the optical deflector 10A has a panel-like shape as a
whole. The optical deflector 10A two-dimensionally deflects incident
light on each in-plane area of the optical deflector 10A; and thus,
incident light can be collected to a predetermined light collection point
in a three-dimensional space.

[0099] The liquid crystal panel 106 is provided at one side of the optical
deflector 10A. A plurality of liquid crystal pixels are arranged in a
matrix in a display region of the liquid crystal panel 106.

[0100] The light emitting unit 107 is provided between the optical
deflector 10A and the liquid crystal panel 106. The light emitting unit
107 includes a light guide plate 110 and a light source 111 which is
provided facing one lateral surface 110a of the light guide plate 110.
The light guide plate 110 has a top surface shaped like an uneven prism
110b. The light source 111 emits light toward the one lateral surface
110a of the light guide plate 110.

[0101] The reflective plate 102 is provided at the other side of the
optical deflector 10A. The reflective plate 102 has a structure similar
to that of the reflective plate 102 in FIG. 1A.

[0102] The pair of stereo cameras 108a and 108b respectively capture
images of a right eye 112a and a left eye 112b of a viewer 112 viewing
the liquid crystal display apparatus 20.

[0103] The control unit 109 controls voltage applied to liquid crystals
103 in the optical deflection elements 101, based on image signals
transmitted from the stereo cameras 108a and 108b. Furthermore, the
control unit 109 controls images to be displayed on the liquid crystal
panel 106, and also controls lighting of the light source 111.

[0104] Next, a description is given of a mechanism of operations performed
by the liquid crystal display apparatus 20 according to Embodiment 1. The
pair of stereo cameras 108a and 108b respectively capture images of the
eyes 112a and 112b of the viewer 112 viewing the liquid crystal panel
106. The control unit 109 detects the positions of the eyes 112a and 112b
of the viewer 112, based on the difference between the images captured by
the stereo cameras 108a and 108b. The control unit 109 controls voltage
to be applied to respective liquid crystal 103 in the optical deflection
elements 101, based on the result of detection, to modulate the
refractive index NL of the liquid crystal 103.

[0105] Light emitted from the light source 111 is incident on the one
lateral surface 110a of the light guide plate 110, propagates through the
light guide plate 110, is bent substantially vertically by the prism 110b
formed on the top surface of the light guide plate 110, and then is
emitted from the bottom surface of the light guide plate 110. After that,
the light passes through the optical deflector 10A, is specularly
reflected by the reflective plate 102, and then passes through the
optical deflector 10A again. The light emitted from the optical deflector
10A passes through the light guide plate 110 and the liquid crystal panel
106, and is emitted to outside of the liquid crystal display apparatus
20. At this time, the liquid crystal panel 106 is illuminated with the
light emitted from the optical deflector 10A, forming an image on the
liquid crystal panel 106.

[0106] From the start of the illumination of the light source 111 till a
predetermined time elapses, the control unit 109 modulates the refractive
index NL of each liquid crystal 103 in the optical deflection elements
101. As a result, the light emitted from the bottom surface of the light
guide plate 110 is deflected by the optical deflector 10A toward the
right eye 112a of the viewer 112 as indicated by a solid arrow 113a in
FIG. 1B. The light emitted from the optical deflector 10A is collected
onto the right eye 112a of the viewer 112. The control unit 109 causes
the liquid crystal panel 106 to display a right-eye image at the time at
which the light is deflected toward the right eye 112a of the viewer 112.

[0107] After the above predetermined time has elapsed, the control unit
109 modulates the refractive index NL of each liquid crystal 103 in the
optical deflection elements 101. As a result, the light emitted from the
bottom surface of the light guide plate 110 is deflected by the optical
deflector 10A toward the left eye 112b of the viewer 112 as indicated by
a dashed arrow 113b in FIG. 1B. The light emitted from the optical
deflector 10A is collected onto the left eye 112b of the viewer 112. The
control unit 109 causes the liquid crystal panel 106 to display a
left-eye image at the time at which the light is deflected toward the
left eye 112b of the viewer 112.

[0108] In this way, the control unit 109 switches the angle of light
deflected by the optical deflector 10A in time series. Accordingly, the
light emitted from the optical deflector 10A is alternately collected
onto the right eye 112a and the left eye 112b of the viewer 112 in time
series. A right-eye image is displayed on the liquid crystal panel 106 at
the time when the light is deflected toward the right eye 112a, and a
left-eye image is displayed on the liquid crystal panel 106 at the time
when the light is deflected toward the left eye 112b of the viewer 112.
As a result, the viewer 112 can recognize a 3D image.

[0109] In the liquid crystal display apparatus 20 according to Embodiment
1, in the manner similar to above, light incident on the optical
deflector 10A passes through the optical deflector 10A, is specularly
reflected by the reflective plate 102, passes through the optical
deflector 10A again, and is emitted from the optical deflector 10A; and
thus, it is possible to increase the light deflection angle. Accordingly,
it is possible to achieve the liquid crystal display apparatus 20 which
provides a greater visual field.

[0110] Furthermore, in a case where a right-eye image and a left-eye image
that are displayed on the liquid crystal panel 106 are the same image,
the viewer 112 recognizes the images as 2D images, but people other than
the viewer 112 cannot recognize the images displayed on the liquid
crystal panel 106. Thus, in such a case, the liquid crystal display
apparatus 20 functions as a privacy display.

[0111] It is to be noted that in Embodiment 1, the top surface of the
light guide plate 110 has a shape of the prism 110b; however, the present
disclosure is not limited to such a structure. As another alternative,
the light emitting unit 107 may have an element other than the light
guide plate 110.

Embodiment 2

[0112]FIG. 2 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 2. As shown in FIG. 2, a liquid crystal
display apparatus 20B according to Embodiment 2 includes a prism sheet
114 (which constitutes an optical element) between an optical deflector
10A and a reflective plate 102. The other elements included in the liquid
crystal display apparatus 20B are similar to those included in the liquid
crystal display apparatus 20 according to Embodiment 1.

[0113] Light emitted from the bottom surface of a light guide plate 110
passes through the optical deflector 10A and the prism sheet 114, is
specularly reflected by the reflective plate 102, and passes through the
prism sheet 114 and the optical deflector 10A again. The light emitted
from the optical deflector 10A passes through the light guide plate 110
and a liquid crystal panel 106, and is emitted to outside of the liquid
crystal display apparatus 20B.

[0114] The prism sheet 114 includes a plurality of prism portions 114a.
The angle of each prism portion 114a is set in such a manner that light
is collected onto an intermediate position between a right eye 112a and a
left eye 112b of a viewer 112 when the viewer 112 is located at a most
appropriate position for viewing 3D images in a state where, for example,
the refractive index NL of a liquid crystal 103 and the refractive index
ND of a dielectric 104 are the same value. Here, the most appropriate
position refers to, for example, a position that is vertically distant
from the center of the liquid crystal panel 160 by distant L.

[0115] Here, a description is given of an example where light is
alternately deflected toward the right eye 112a and the left eye 112b of
the viewer 112 when the distance L is 300 mm, the width W2 of the liquid
crystal panel 106 is 200 mm, and the distance D between the right eye
112a and the left eye 112b of the viewer 112 is 60 mm. In a case where
the prism sheet 114 is not included, it is necessary to set the light
deflection angle to approximately 13 degrees to deflect light from, for
example, one end of the liquid crystal panel 106 (left end in FIG. 2)
toward the right eye 112a of the viewer 112. Furthermore, it is necessary
to set the light deflection angle to approximately 23 degrees to deflect
light from one end of the liquid crystal panel 106 toward the left eye
112b of the viewer 112. For example, in the case of the optical deflector
10A where the liquid crystal 103 has a height H of 15 μm and a width
W1 of 50 μm, when the difference between the refractive index NL of
the liquid crystal 103 and the refractive index ND of the dielectric 104
is 0.1, light is deflected at an angle of approximately 5.2 degrees.
Hence, it is necessary to set the difference between the refractive index
NL of the liquid crystal 103 and the refractive index ND of the
dielectric 104 to 0.45, to deflect light at an angle of approximately 23
degrees. As another alternative, the height of the optical deflection
elements 101 included in the optical deflector 10A needs to be increased.

[0116] On the other hand, in a case where the liquid crystal display
apparatus 20B includes the prism sheet 114 as in Embodiment 2, light is
deflected by the prism sheet 114 toward the intermediate position between
the right eye 112a and the left eye 112b of the viewer 112, with the
difference between the refractive index NL of the liquid crystal 103 and
the refractive index ND of the dielectric 104 being 0. Thus, for example,
light emitted from one end of the liquid crystal panel 106 is deflected
at an angle of approximately 18 degrees toward the intermediate position
between the right eye 112a and the left eye 112b of the viewer 112, with
the difference between the refractive index NL of the liquid crystal 103
and the refractive index ND of the dielectric 104 being 0. In this state,
it is possible to deflect light toward the right eye 112a and the left
eye 112b of the viewer 112 by setting the difference between the
refractive index NL of the liquid crystal 103 and the refractive index ND
of the dielectric 104 to ±0.1 and modulating the angle of light
deflected by the optical deflector 10A by approximately ±5 degrees.

[0117] Accordingly, the liquid crystal display apparatus 20B according to
Embodiment 2 can deflect light toward the right eye 112a and the left eye
112b of the viewer 112, with the small difference between the refractive
index NL of the liquid crystal 103 and the refractive index ND of the
dielectric 104, or with the small height of the optical deflection
elements 101 included in the optical deflector 10A. Furthermore, the
difference between the refractive index NL of the liquid crystal 103 and
the refractive index ND of the dielectric 104 depends on the value of
voltage applied to the liquid crystal 103; and thus, smaller difference
between the refractive indexes leads to lower voltage applied to the
liquid crystal 103. As a result, it is possible to achieve the liquid
crystal display apparatus 20B which consumes lower power. Furthermore,
small height of the optical deflection elements 101 included in the
optical deflector 10A leads to the liquid crystal display apparatus 20B
with excellent processing characteristics.

[0118] Note that in Embodiment 2, the prism sheet 114 is used as an
optical element; however, the present disclosure is not limited to this.
For example, a Fresnel sheet may be used as an optical element.

Embodiment 3

[0119]FIG. 3 is a cross-sectional view of an optical deflection apparatus
according to Embodiment 3. As shown in FIG. 3, an optical deflection
apparatus 30 according to Embodiment 3 includes an optical deflector 10,
a polarizing reflective sheet 121, a λ/4 plate 122, a light
emitting unit 107, and a reflective plate 102.

[0120] In the similar manner to Embodiment 1, the optical deflector 10
includes an optical deflection element 101 having a liquid crystal 103
and a dielectric 104.

[0121] The polarizing reflective sheet 121 is provided at one side of the
optical deflector 10, that is, at the side closer to the dielectric 104.
The polarizing reflective sheet 121 is a sheet which reflects light
having a first polarization direction (for example, a direction vertical
relative to the sheet of FIG. 3), and which transmits light having a
second polarization direction (for example, an in-plane direction in FIG.
3) perpendicular to the first deflection direction.

[0122] The reflective plate 102 is provided at the other side of the
optical deflector 10, that is, at the side closer to the crystal 103. The
reflective plate 102 has the similar functions to those of the reflective
plate 102 according to Embodiment 1.

[0123] The λ/4 plate 122 is provided between the optical deflector
10 and the reflective plate 102. The λ/4 plate 122 is a wave plate
which has a function to convert linear polarization with a given
wavelength into circular polarization (or convert circular polarization
into linear polarization), and has a function to generate phase
difference of 1/4 of wavelength λ (that is, phase difference of 90
degrees) between linear polarization which oscillate in a direction
vertical to each other.

[0124] The light emitting unit 107 is provided between the optical
deflector 10 and the polarizing reflective sheet 121. The light emitting
unit 107 includes a light source (not shown) and a reflective plate 123.
Light emitted from the light source is specularly reflected by the
reflective plate 123, and then is emitted toward the polarizing
reflective sheet 121. The light emitted toward the polarizing reflective
sheet 121 has a first polarization direction.

[0125] Next, a description is given of a method for deflecting light
performed by the optical deflection apparatus 30 according to Embodiment
3. For example, a description is given of a case where the liquid crystal
103 has a refractive index NL of 1.5, a height H of 15 μm, a width W1
of 50 μm, and the dielectric 104 has a refractive index ND of 1.4.
Since light, incident on the polarizing reflective sheet 121 from the
reflective plate 123 at an angle of, for example, θ1=1.7 degrees,
has a first polarization direction, the light is reflected by the
polarizing reflective sheet 121. The light reflected by the polarizing
reflective sheet 121 is incident on the dielectric 104 of the optical
deflection element 101, travels through the dielectric 104, and is
refracted at the interface between the dielectric 104 and the liquid
crystal 103 at an angle of, for example, θ2=2.3 degrees. After
that, the light travels through the liquid crystal 103, and is emitted
into the air at an angle of, for example, θ3=3.4 degrees. The light
emitted into the air is converted from linear polarization into circular
polarization by passing through the λ/4 plate 122, and is converted
from circular polarization into linear polarization by being specularly
reflected by the reflective plate 102 and then passing through the
λ/4 plate 122 again. The light emitted from the λ/4 plate 122
is incident on the liquid crystal 103 of the optical deflection element
101 again at an angle of, for example, θ3=3.4 degrees, with being
polarized in the second polarization direction.

[0126] After that, the light is refracted at the interface between the air
and the liquid crystal 103 at an angle of θ4=2.3 degrees, travels
through the liquid crystal 103, and is refracted at the interface between
the liquid crystal 103 and the dielectric 104 at an angle of, for
example, θ5=3.7 degrees. The light traveled through the dielectric
104 is emitted from the dielectric 104 at an angle of, for example,
θ6=5.2 degrees, and then is incident on the polarizing reflective
sheet 121. Since the light incident on the polarizing reflective sheet
121 has a second polarization direction, the light passes through the
polarizing reflective sheet 121, and is emitted to outside of the optical
deflection apparatus 30. Hence, the angle of light deflected by the
optical deflection apparatus 30 according to Embodiment 3 is the angle
θ6=5.2 degrees, that is, the angle approximately three times as
large as the angle θ1. Furthermore, each of the angles 81 to 86 is
an angle relative to the vertical direction.

[0127] As described, according to the optical deflection apparatus 30
according to Embodiment 3, light incident on the optical deflector 10 is
emitted from the optical deflector 10 after passing through the optical
deflector 10 twice. Accordingly, it is possible to further increase the
light deflection angle with a simple structure.

Embodiment 4

Structure of Light Deflection Apparatus

[0128]FIG. 4A is a cross-sectional view of an optical deflection
apparatus according to Embodiment 4. As shown in FIG. 4A, an optical
deflection apparatus 30C according to Embodiment 4 includes a light
emitting unit 107 between an optical deflector 10 and a λ/4 plate
122. Light emitted from a light source (not shown) has a first
polarization direction, and is emitted toward the optical deflector 10
after being specularly reflected by the reflective plate 123. The other
elements included in the optical deflection apparatus 30C are similar to
those included in the optical deflection apparatus 30 according to
Embodiment 3.

[0129] Next, a description is given of a method for deflecting light
performed by the optical deflection apparatus 30C according to Embodiment
4. A description is given of an example where a liquid crystal 103 has a
refractive index NL of 1.5, a height H of 15 μm, and a width W1 of 50
μm, and a dielectric 104 has a refractive index ND of 1.4. Light
incident on the crystal 103 of the optical deflector 10 from the
reflective plate 123 is refracted at the interface between the liquid
crystal 103 and the dielectric 104 at an angle of, for example,
θ0=1.2 degrees. Then, the light travels through the dielectric 104,
and is emitted from the dielectric 104 at angle of, for example,
θ1=1.7 degrees. After that, the light passes through the optical
deflector 10 along the path similar to that in Embodiment 3, and is
emitted from the dielectric 104 at an angle of, for example, θ6=5.2
degrees. Hence, the angle of light deflected by the optical deflection
apparatus 30C according to Embodiment 4 is the angle θ6=5.2
degrees, that is, the angle approximately three times as large as the
angle θ1. Furthermore, each of the angles θ0 to θ6 is
an angle relative to the vertical direction.

[0130] As described, in the optical deflection apparatus 30C according to
Embodiment 4, light incident on the optical deflector 10 is emitted from
the optical deflector 10 after passing through the optical deflector 10
three times. Accordingly, it is possible to further increase the light
deflection angle with a simple structure, in the similar manner to
Embodiment 3.

(Structure of Liquid Crystal Display Apparatus)

[0131]FIG. 4B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 4. As shown in FIG. 4B, a liquid
crystal display apparatus 20C according to Embodiment 4 includes the
optical deflection apparatus 30C, and a liquid crystal panel 106 on which
light emitted from the optical deflection apparatus 30C is incident. The
liquid crystal panel 106 is provided at one side of the optical
deflection apparatus 30C, which is the side closer to a polarizing
reflective sheet 121. The optical deflector 10A of the optical deflection
apparatus 30C includes an array of the optical deflection elements 101. A
light emitting unit 107 of the optical deflection apparatus 30C includes
a light guide plate 110 and a light source 111 in the similar manner to
the light emitting unit 107 according to Embodiment 1. Light emitted from
the light source 111 has a first polarization direction. The other
elements included in the liquid crystal display apparatus 20C are similar
to those included in the liquid crystal display apparatus 20 according to
Embodiment 1.

[0132] The light emitted from the light guide plate 110 of the light
emitting unit 107 is incident on an optical deflector 10A, passes through
the optical deflector 10A three times, and then is emitted from the
optical deflector 10A, as in the similar manner to above. Accordingly,
the liquid crystal display apparatus 20C according to Embodiment 4 can
further increase the light deflection angle. As a result, it is possible
to achieve the liquid crystal display apparatus 20C which provides a
greater visual field with a relatively simple structure.

[0133] Furthermore, the optical deflection apparatus 30 according to
Embodiment 3 can also constitute a liquid crystal display apparatus by
providing the liquid crystal panel 106 at one side of the optical
deflection apparatus 30 in the similar manner.

Embodiment 5

[0134] FIG. 5 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 5. As shown in FIG. 5, a liquid crystal
display apparatus 20D according to Embodiment 5 includes a polymer liquid
crystal diffuser panel 124 (which constitutes a diffuser panel) between a
liquid crystal panel 106 and an optical deflection apparatus 30C. A
control unit 109 controls voltage to be applied to the polymer liquid
crystal diffuser panel 124. In a state where voltage is not applied to
the polymer liquid crystal diffuser panel 124 by the control unit 109,
the polymer liquid crystal diffuser panel 124 has translucent white color
and is kept in a diffusion state where light is diffused. In a state
where voltage is applied to the polymer liquid crystal diffuser panel 124
by the control unit 109, the polymer liquid crystal diffuser panel 124 is
transparent and is kept in a non-diffusion state where light is
transmitted without diffusion. Accordingly, the polymer liquid crystal
diffuser panel 124 can be switched between the diffusion state and the
non-diffusion state by the control unit 109.

[0135] In a case where the liquid crystal display apparatus 20D is used as
a 3D display or a privacy display, the polymer liquid crystal diffuser
panel 124 is kept in the non-diffusion state by applying voltage to the
polymer liquid crystal diffuser panel 124. In this way, light can be
alternately deflected toward a right eye 112a and a left eye 112b of a
viewer 112 in a state where polymer liquid crystal diffuser panel 124
does not diffuse light.

[0136] On the other hand, in a case where the liquid crystal display
apparatus 20D is used as a 2D display, the polymer liquid crystal
diffuser panel 124 is kept in a diffusion state by not applying voltage
to the polymer liquid crystal diffuser panel 124, and the refractive
index NL of the liquid crystal 103 and the refractive index ND of the
dielectric 104 are set to the same value. Accordingly, light emitted from
the optical deflection apparatus 30C is incident on the liquid crystal
panel 106 in a diffused state, thereby illuminating the liquid crystal
panel 106 at a greater angle.

[0137] With this, it is possible to achieve the liquid crystal display
apparatus 20D which is switchable between 2D display and 3D display or
privacy display.

[0138] In Embodiment 5, the polymer liquid crystal diffuser panel 124 is
used as a diffuser panel which is switchable between a diffusion state
and a non-diffusion state; however, the present disclosure is not limited
to this, and any other units including the similar function may be used.

Embodiment 6

[0139]FIG. 6A and FIG. 6B are cross-sectional views of a liquid crystal
display apparatus according to Embodiment 6. As shown in FIG. 6A, a
liquid crystal display apparatus 20E according to Embodiment 6 includes a
λ/2 plate 125 between a light source 111 and a light guide plate
110. The other elements included in the liquid crystal display apparatus
20E are similar to those included in the liquid crystal display apparatus
20D according to Embodiment 5.

[0140] The λ/2 plate 125 is a wave plate which has a function to
convert linear polarization with a given oscillation direction into
linear polarization with a oscillation direction orthogonal to the
oscillation direction of the linear polarization, and has a function to
generate phase difference of 1/2 of wavelength λ (that is, phase
difference of 180 degrees) between linear polarization which oscillate in
a direction vertical to each other. By rotating the position of the
λ/2 plate 125 about an optical axis, it is possible to switch the
polarization direction of light passed through the λ/2 plate 125.
Hence, even when light emitted from the light source 111 has a single
polarization, it is possible to modulate the polarization direction of
light incident on the light guide plate 110 by rotating the position of
the λ/2 plate 125 about the optical axis. For example, in a case
where the λ/2 plate 125 is positioned at a first rotation position,
light is polarized in a first polarization direction, and where the
λ/2 plate 125 is positioned at a second rotation position, light is
polarized in a second polarization direction.

[0141] When light, which is polarized in the second polarization direction
by positioning the λ/2 plate 125 at the second rotation position,
is incident on the light guide plate 110, the light arrived at the
polarizing reflective sheet 121 passes through the polarizing reflective
sheet 121. For example, in a case where the liquid crystal display
apparatus 20E is used as a 2D display, light arrives at the polymer
liquid crystal diffuser panel 124 without passing through the optical
deflector 10A a plurality of times, by polarizing light incident on the
light guide plate 110 in the second deflection direction, and by setting
the refractive index NL of the liquid crystal 103 and the refractive
index ND of the dielectric 104 of the optical deflector 10A to the same
value. Accordingly, it is possible to reduce light loss caused by light
passing extra path, resulting in increasing light use efficiency of the
liquid crystal display apparatus 20E as a 2D display.

[0142] Furthermore, when light polarized in the first polarization
direction is incident on the light guide plate 110 by positioning the
λ/2 plate 125 at the first rotation position, the light arrived at
the polarizing reflective sheet 121 is reflected by the polarizing
reflective sheet 121. After that, the light passes through the optical
deflector 10A twice, and passes through the polarizing reflective sheet
121. Accordingly, the liquid crystal display apparatus 20E may be used as
a 3D display or a privacy display.

[0143] In Embodiment 6, the λ/2 plate 125 is used as a unit for
switching the polarization direction of light; however, the present
disclosure is not limited to this, but other units may be used.

[0144] Furthermore, by adjusting the position of the λ/2 plate 125
to a position between the first rotation position and the second rotation
position, the polarization direction of light which passed through the
λ/2 plate 125 includes polarization components of both the first
polarization direction and the second polarization direction. As shown in
FIG. 6B, light, having polarization components of the second polarization
direction, passes through the optical deflector 10A once, passes through
the polarizing reflective sheet 121, and is deflected toward the eyes
112a and 112b of the viewer 112. Light, having polarization components of
the first polarization direction, passes through the optical deflector
10A three times, passes through the polarizing reflective sheet 121, and
is deflected toward eyes 126a and 126b of a viewer 126. In this way, the
polarization direction of light incident on the light guide plate 110
includes the polarization components of both of the first polarization
direction and the second polarization direction; and thus, light can be
deflected concurrently in two directions of the viewer 112 and the viewer
126. Accordingly, it is possible for the viewers 112 and 126 to
concurrently view 3D images displayed on the liquid crystal panel 106.

Embodiment 7

[0145] FIG. 7 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 7. As shown in FIG. 7, in a liquid
crystal display apparatus 20F according to Embodiment 7, an optical
deflection apparatus 30F includes a first optical deflector 10Aa and a
second optical deflector 10Ab, as optical deflectors. The first optical
deflector 10Aa is provided between a light guide plate 110 of a light
emitting unit 107 and a polarizing reflective sheet 121. The second
optical deflector 10Ab is provided between the light guide plate 110 of
the light emitting unit 107 and a λ/4 plate 122. The first optical
deflector 10Aa and the second optical deflector 10Ab include a structure
similar to those of the optical deflector 10A according to Embodiment 6.
The other elements included in the liquid crystal display apparatus 20F
are similar to those included in the liquid crystal display apparatus 20E
according to Embodiment 6.

[0146] Next, a description is given of a mechanism of operations performed
by the liquid crystal display apparatus 20F according to Embodiment 7. A
polymer liquid crystal diffuser panel 124 is kept in a non-diffusion
state by a control unit 109. In the similar manner to Embodiment 6, the
polarization direction of light which passed through the λ/2 plate
125 includes the polarization components of both the first polarization
direction and the second polarization direction. Light, having the second
polarization direction components, is emitted from the light guide plate
110, passes through the optical deflector 10Aa only once, and then passes
through the polarizing reflective sheet 121. After that, the light is
incident on the liquid crystal panel 106, is emitted from the liquid
crystal panel 106, and is deflected toward eyes 112a and 112b of a viewer
112.

[0147] Light, having the first polarization direction components, is
emitted from the light guide plate 110, passes through the optical
deflector 10Aa, and then is reflected by the polarizing reflective sheet
121. After that, the light passes through the optical deflector 10Aa
again, further passes through the optical deflector 10Ab, and then is
incident on the λ/4 plate 122. The light reflected by the
reflective plate 102 passes through the optical deflector 10Ab and the
optical deflector 10Aa again, passes through the polarizing reflective
sheet 121, and then is incident on the liquid crystal panel 106.
Accordingly, the light emitted from the liquid crystal panel 106 is
deflected toward eyes 126a and 126b of a viewer 126. As a result,
according to the liquid crystal display apparatus 20F in Embodiment 7, it
is possible for the viewers 112 and 126 to concurrently view 3D images
displayed on the liquid crystal panel 106.

[0148] As described, light deflected by passing through the optical
deflector 10Aa once is collected onto the eyes 112a and 112b of the
viewer 112, and light deflected by passing through the optical deflector
10Aa three times and the optical deflector 10Ab twice is collected onto
the eyes 126a and 126b of the viewer 126. After determining refractive
index NL of a liquid crystal 103 included in the optical deflector 10Aa
to deflect light toward the viewer 112, and refractive index NL of a
liquid crystal 103 included in the optical deflector 10Ab is determined
to deflect light toward the viewer 126. As a result, it is possible to
independently deflect light toward the viewer 112 and the viewer 126 even
when they are located at different positions.

[0149] By arbitrary setting the ratio of light having the first
polarization direction components and the ratio of light having the
second polarization direction components to light incident on the light
guide plate 110, it is possible to arbitrary set the ratio of an amount
of light independently deflected toward the viewer 112 and the viewer
126.

Embodiment 8

[0150] FIG. 8 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 8. As shown in FIG. 8, a liquid crystal
display apparatus 20G according to Embodiment 8 includes a prism sheet
114 (which constitutes an optical element) between a light guide plate
110 of a light emitting unit 107 and a λ/4 plate 122. The prism
sheet 114 have a similar structure to that of the prism sheet 114
according to Embodiment 2. The other elements included in the liquid
crystal display apparatus 20G are similar to those included in the liquid
crystal display apparatus 20E according to Embodiment 6.

[0151] In the similar manner to Embodiment 6, the polarization direction
of light which passed through the λ/2 plate 125 is switchable
between the first polarization direction and the second polarization
direction. When light, polarized in the second polarization direction, is
incident on the light guide plate 110, the light arrived at a polarizing
reflective sheet 121 passes through the polarizing reflective sheet 121.
When light polarized in the first polarization direction is incident on
the light guide plate 110, the light arrived at the polarizing reflective
sheet 121 is reflected by the polarizing reflective sheet 121, and passes
through the optical deflector 10A twice. Here, while the light travels
back and forth between the polarizing reflective sheet 121 and the
reflective plate 102, the light passes through the prism sheet 114 twice.

[0152] Accordingly, the advantageous effects similar to those in
Embodiment 2 can be obtained by including the prism sheet 114 in the
liquid crystal display apparatus 20G according to Embodiment 8.

[0153] In Embodiment 8, the prism sheet 114 is provided between the light
guide plate 110 and the λ/4 plate 122; however, the prism sheet 114
may be provided between the λ/4 plate 122 and the reflective plate
102. Furthermore, in a case where the liquid crystal display apparatus
20G is used as a 2D display, light polarized in the second polarization
direction does not pass through the prism sheet 114 by positioning the
prism sheet 114 at a position lower than the light guide plate 110.
Hence, the prism sheet 114 does not affect viewing angle of 2D images.

[0154] Note that in Embodiment 8, the prism sheet 114 is used as an
optical element; however, the present disclosure is not limited to this.
For example, a Fresnel sheet may be used as an optical element.

Embodiment 9

[0155]FIG. 9 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 9. As shown in FIG. 9, a liquid crystal
display apparatus 20H according to Embodiment 9 includes an actuator 127
for moving a prism sheet 114H to the deflection direction of light
(horizontal direction in FIG. 9). By moving the prism sheet 114H to the
light deflection direction using the actuator 127, it is possible to
horizontally adjust the collection point of light emitted from a liquid
crystal panel 106. The prism sheet 114H according to Embodiment 9 is an
active optical element which is capable of modulating a collection point
of light emitted from the liquid crystal panel 106, according to the
movement of a right eye 112a and a left eye 112b of a viewer 112.

[0156] In a case where the position of the viewer 112 moves horizontally
as indicated by arrows 128a and 128b in FIG. 9, the position of the
viewer 112 is detected by a pair of stereo cameras 108a and 108b. A
control unit 109 drives the actuator 127 based on detection signals from
the pair of stereo cameras 108a and 108b. As a result, the prism sheet
114H is moved horizontally by the actuator 127 as indicated by arrows
129a and 129b in FIG. 9. For example, in a case where the position of the
viewer 122 is moved in the direction indicated by the arrow 128a, the
actuator 127 is driven based on a command from the control unit 109, and
the prism sheet 114H is moved by a predetermined amount in the direction
indicated by the arrow 129a. More specifically, by driving the actuator
127 to adjust the position of the prism sheet 114H based on the detected
positions of the right eye 112a and the left eye 112b of the viewer 112,
it is possible to continuously collect light from the liquid crystal
panel 106 onto the right eye 112a and the left eye 112b of the viewer 112
even when the position of the viewer 112 is moved. As a result, the
viewer 112 is capable of continuously viewing 3D images and the like.

[0157] In the liquid crystal display apparatus 20H according to Embodiment
9, an optical deflector 10A deflects light toward the right eye 112a and
the left eye 112b of the viewer 112, and the prism sheet 114H driven by
the actuator 127 follows the light collection point moved along the
movement of the right eye 112a and the left eye 112b of the viewer 112.
This provides the following advantageous effects. For example, in a case
where images are displayed on the liquid crystal panel 106 at a frequency
of 60 Hz, the speed for deflecting light (deflection speed) toward the
right eye 112a and the left eye 112b of the viewer 112 needs to be a few
milliseconds (120 Hz). In order to increase the deflection speed of the
optical deflector 10A, the height H of a liquid crystal 103 of the
optical deflector 10A needs to be lower as much as possible; however, in
such a case, it is difficult to increase the angle of light deflected by
the optical deflector 10A. On the other hand, following the light
collection point moved along with the movement of the positions of the
right eye 112a and the left eye 112b of the viewer 112 does not require a
fast response speed such as a few milliseconds that is required when
deflecting light toward the right eye 112a and the left eye 112b of the
viewer 112.

[0158] Accordingly, as in the liquid crystal display apparatus 20H
according to Embodiment 9, the optical deflector 10A deflects light
toward the right eye 112a and the left eye 112b of the viewer 112, which
requires a fast response speed, and the prism sheet 114H follows the
light collection point moved along with the movement of the right eye
112a and the left eye 112b of the viewer 112, which does not require a
fast response speed. As a result, it is possible to achieve the liquid
crystal display apparatus 20H which provides a greater visual field, in
which the light collection point can be easily followed even when the
position of the viewer significantly shifts.

[0159] In Embodiment 9, the prism sheet 114H driven by the actuator 127 is
used as an active optical element; however, any other units, such as a
liquid crystal lens, may be used which have the similar functions.

[0160] Furthermore, in the liquid crystal display apparatus 20B according
to Embodiment 2, too, the prism sheet 114 may be configured as an active
optical element driven by the actuator 127, as in Embodiment 9.

Embodiment 10

Structure of Light Deflection Apparatus

[0161] FIG. 10A is a cross-sectional view of an optical deflection
apparatus according to Embodiment 10. As shown in FIG. 10A, an optical
deflection apparatus 30J according to Embodiment 10 includes a reflective
plate 102 at one side of an optical deflector 10. A λ/4 plate 122
is provided between the optical deflector 10 and the reflective plate
102. A polarizing reflective sheet 121 is provided at the other side of
the optical deflector 10. A light emitting unit 107 is provided between
the optical deflector 10 and the polarizing reflective sheet 121. Light
emitted from a light source (not shown) has a second polarization
direction, is specularly reflected by the reflective plate 123, and is
emitted toward the optical deflector 10.

[0162] Next, a description is given of a method for deflecting light
performed by the optical deflection apparatus 30J according to Embodiment
10. For example, a description is given of a case where a liquid crystal
103 has a refractive index NL of is 1.5, a height H of 15 μm, and a
width W1 of 50 μm, and a dielectric 104 has a refractive index ND of
1.4.

[0163] Light incident on the crystal 103 of the optical deflector 10 from
the reflective plate 123 in a substantially vertical direction is
refracted at the interface between the liquid crystal 103 and the
dielectric 104 at an angle of, for example, θ0=1.2 degrees. Then,
the light travels through the dielectric 104, and is emitted from the
dielectric 104 into the air at an angle of, for example, θ1=1.7
degrees. The light emitted from the dielectric 104 is converted from
linear polarization into circular polarization by passing through the
λ/4 plate 122, and is converted from circular polarization into
linear polarization by being specularly reflected by the reflective plate
102 and passing through the λ/4 plate 122 again. The light emitted
from the λ/4 plate 122 is incident on the dielectric 104 of the
optical deflection element 101 again with being polarized in the first
polarization direction. After that, the light travels through the
dielectric 104, and is refracted at the interface between the dielectric
104 and the liquid crystal 103 at an angle of, for example, θ2=2.3
degrees. The light which traveled through the liquid crystal 103 is
emitted from the liquid crystal 103 at an angle of, for example,
θ3=3.4 degrees, and then is incident on the polarizing reflective
sheet 121. Since the light incident on the polarizing reflective sheet
121 has a first polarization direction, the light is reflected by the
polarizing reflective sheet 121, and is incident on the liquid crystal
103 again at an angle of, for example, θ3=3.4 degrees.

[0164] After that, the light is refracted at the interface between the air
and the liquid crystal 103 at an angle of, for example, θ4=2.3
degrees, travels through the liquid crystal 103, and is refracted at the
interface between the liquid crystal 103 and the dielectric 104 at an
angle of, for example, θ5=3.7 degrees. The light which traveled
through the dielectric 104 is emitted from the dielectric 104 into the
air at an angle of, for example, θ6=5.2 degrees, passes through the
λ/4 plate 122, and is specularly reflected by the reflective plate
102. By the light specularly reflected by the reflective plate 102
passing through the λ/4 plate 122 again, the light emitted from the
λ/4 plate 122 is incident on the dielectric 104 of the optical
deflection element 101 again with being polarized in the second
polarization direction.

[0165] The light incident on the dielectric 104 is refracted at the
interface between the air and the dielectric 104 at an angle of, for
example, θ7=3.7 degrees, travels through the dielectric 104, and is
refracted at the interface between the dielectric 104 and the liquid
crystal 103 at an angle of, for example, θ8=4.6 degrees. The light
which traveled through the liquid crystal 103 is emitted from the liquid
crystal 103 at an angle of, for example, θ9=6.9 degrees, and then
is incident on the polarizing reflective sheet 121. Since the light
incident on the polarizing reflective sheet 121 has the second
polarization direction, the light passes through the polarizing
reflective sheet 121, and is emitted to outside. Hence, the angle of
light deflected by the optical deflection apparatus 30J according to
Embodiment 10 is the angle θ9=6.9 degrees, that is, the angle four
times as large as the angle θ1. Furthermore, each of the angles
θ0 to θ9 is an angle relative to the vertical direction.

[0166] As described, in the optical deflection apparatus 30J according to
Embodiment 10, light incident on the optical deflector 10 is emitted from
the optical deflector 10 after passing through the optical deflector 10
four times. Such a simple structure allows the light deflection angle to
be further increased.

[0167] As described in Embodiments 1, 3, and 4, the deflection angle of
light which passes through the optical deflector 10 once is 1.7 degrees,
the deflection angle of light which passes through the optical deflector
10 twice is 3.4 degrees, and the deflection angle of light which passes
through the optical deflector 10 three times is 5.2 degrees. In
Embodiment 10, the deflection angle of light which passes through the
optical deflector 10 four times is 6.9 degrees. Hence, it is understood
that each time light is deflected by the optical deflector 10, the light
deflection angle of 1.7 degrees is added.

[0168] In a conventional method where the light deflection angle is
increased by using the lens array 608 shown in FIG. 15B, in a case where
the incident angle is different from the design value by, for example, 1
degree, when the angle is increased by the lens array 608, the deflection
angle of light emitted from the lens array 608 is increased by a
magnification factor of the lens array 608. More specifically, in a case
where the light deflection angle is quadruplicated by the lens array 608
and the incident angle is different from the design value by 1 degree,
the outgoing angle is different from the design value by 4 degrees. In
contrast, in the optical deflection apparatus 30J according to Embodiment
10, light is deflected by the optical deflector 10 a plurality of times;
and thus, the amount of the outgoing angle different from the design
value does not vary. More specifically, in a case where light is
deflected by the optical deflector 10 four times and the incident angle
is different from the design value by 1 degree, the outgoing angle is
different from the design value by 1 degree. Accordingly, it is possible
for the optical deflection apparatus 30J according to Embodiment 10 to
deflect light with high accuracy and less errors.

(Structure of Liquid Crystal Display Apparatus)

[0169] FIG. 10B is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 10. As shown in FIG. 10B, the liquid
crystal display apparatus 20J according to Embodiment 10 includes the
optical deflection apparatus 30J, and a liquid crystal panel 106 on which
the light emitted from the optical deflection apparatus 30J is incident.
The liquid crystal panel 106 is provided at one side of the optical
deflection apparatus 30J which is closer to the polarizing reflective
sheet 121. An optical deflector 10A of the optical deflection apparatus
30J includes an array of optical deflection elements 101. A light
emitting unit 107 of the optical deflection apparatus 30J includes a
light guide plate 110 and a light source 111 in the similar manner to the
light emitting unit 107 according to Embodiment 1. Light emitted from the
light source 111 is polarized in a second polarization direction. The
other elements included in the liquid crystal display apparatus 20J are
similar to those included in the liquid crystal display apparatus 20
according to Embodiment 1.

[0170] The light emitted from the light guide plate 110 of the light
emitting unit 107 is incident on the optical deflector 10A, passes
through the optical deflector 10A four times, and then is emitted from
the optical deflector 10A, as in the similar manner to above.
Accordingly, in the liquid crystal display apparatus 20J according to
Embodiment 10, it is possible to further increase the light deflection
angle. As a result, it is possible to achieve the liquid crystal display
apparatus 20J which provides a greater visual field with a relatively
simple structure.

Embodiment 11

[0171]FIG. 11 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 11. As shown in FIG. 11, a liquid
crystal display apparatus 20K according to Embodiment 11 includes a
polymer liquid crystal diffuser panel 124 (which constitutes a diffuser
panel) between a liquid crystal panel 106 and an optical deflection
apparatus 30J. The polymer liquid crystal diffuser panel 124 has a
structure similar to that of the polymer liquid crystal diffuser panel
124 according to Embodiment 5. The other elements included in the liquid
crystal display apparatus 20K are similar to those included in the liquid
crystal display apparatus 20J according to Embodiment 10.

[0172] Accordingly, it is possible to achieve the liquid crystal display
apparatus 20K which is switchable between 2D display and 3D display or
privacy display, in the similar manner to Embodiment 5.

[0173] In a case where the liquid crystal display apparatus 20K is used as
a 2D display, by making the polarization direction of light incident on
the light guide plate to a first polarization direction, light emitted
from the light guide plate 110 is emitted from the polarizing reflective
sheet 121 after traveling back and forth between an optical deflector 10A
and the light guide plate 110. As a result, it is possible to reduce
light loss caused when light passes through an optical material such as
the optical deflector 10A, leading to the liquid crystal display
apparatus 20K with higher light use efficiency.

Embodiment 12

[0174] FIG. 12 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 12. As shown in FIG. 12, a liquid
crystal display apparatus 20L according to Embodiment 12 includes a
λ/2 plate 125 between a light source 111 and a light guide plate
110. The λ/2 plate 125 has a structure similar to that of the
λ/2 plate 125 according to Embodiment 6. The other elements
included in the liquid crystal display apparatus 20L are similar to those
included in the liquid crystal display apparatus 20K according to
Embodiment 11.

[0175] In the similar manner to Embodiment 6, the polarization direction
of light passed through the λ/2 plate 125 includes the polarization
components of both the first polarization direction and the second
polarization direction. In a case where light, having first polarization
direction components, is incident on the light guide plate 110, the light
passes through the optical deflector 10A twice, arrives at the polarizing
reflective sheet 121, and passes through the polarizing reflective sheet
121. Accordingly, the light emitted from the liquid crystal panel 106 is
deflected toward eyes 112a and 112b of a viewer 112.

[0176] In a case where light, having second polarization direction
components, is incident on the light guide plate 110, the light passes
through the optical deflector 10A twice, arrives at the polarizing
reflective sheet 121, is reflected by the polarizing reflective sheet
121, and further passes through the optical deflector 10A twice. After
that, the light passes through the polarizing reflective sheet 121, and
the light emitted from the liquid crystal panel 106 is deflected toward
eyes 126a and 126b of a viewer 126.

[0177] Accordingly, in Embodiment 12, in the similar manner to Embodiment
6, two viewers 112 and 126 are capable of concurrently viewing 3D images
and the like displayed on the liquid crystal panel 106. Furthermore, by
switching the polarization direction of light incident on the light guide
plate 110 between the first polarization direction and the second
polarization direction, it is possible to switch a viewer who is allowed
to view 3D images and the like between the viewer 112 and the viewer 126.

Embodiment 13

[0178] FIG. 13 is a cross-sectional view of a liquid crystal display
apparatus according to Embodiment 13. As shown in FIG. 13, a liquid
crystal display apparatus 20M according to Embodiment 13 includes a prism
sheet 114 (which constitutes an optical element) between an optical
deflector 10A and a λ/4 plate 122. The prism sheet 114 has a
structure similar to that of the prism sheet 114 according to Embodiment
2. The other elements included in the liquid crystal display apparatus
20M are similar to those included in the liquid crystal display apparatus
20L according to Embodiment 13.

[0179] Accordingly, advantageous effects similar to those in Embodiment 2
can be obtained by including the prism sheet 114 in the liquid crystal
display apparatus 20M according to Embodiment 13.

[0180] In Embodiment 13, the prism sheet 114 is provided between the
optical deflector 10A and the λ/4 plate 122; however, the prism
sheet 114 may be provided between the λ/4 plate 122 and the
reflective plate 102. Furthermore, in Embodiment 13, the prism sheet 114
is used as an optical element; however, the present disclosure is not
limited to this. For example, a Fresnel sheet may be used as an optical
element.

[0181] Furthermore, in Embodiment 13, too, the prism sheet 114 may be
configured as an active optical element driven by an actuator as in
Embodiment 9.

[0182] While the above has been a description of Embodiments 1 to 13 of
the present disclosure, the structure described in each of Embodiments 1
to 13 is merely an example, and it goes without saying that various
modifications are possible within a scope that does not depart from the
gist of the invention. Furthermore, it is of course possible to combine
Embodiments 1 to 13 described above, or combine modifications.

INDUSTRIAL APPLICABILITY

[0183] The present disclosure is applicable to an optical deflector and an
optical deflection apparatus which provide greater light deflection
angle. Furthermore, the present disclosure may also be applicable to a
liquid crystal display apparatus which displays high-quality 3D images
and the like with a greater visual field in which 3D images and the like
are viewable and with reduced crosstalk.